1. Field of the Invention
This invention relates generally to wireless local area networks, and more particularly to a hybrid iterative minimum mean-squared error estimation (IMMSE)—linear minimum mean-squared error estimation (LMMSE) receiver processing technique and apparatus for a multiple-input multiple-output (MIMO) wireless local area network (WLAN).
2. Description of the Prior Art
The performance of the next-generation MIMO WLANs depends heavily on the signal processing performed at the receiver. Foschini et al. in 1996, proposed a novel technique that exploits the channel multipaths in MIMO systems to achieve near-Shannon capacity. This technique, referred to as Bell Labs Layered Space-Time Architecture (BLAST), operates on a “cancellation” and “nulling” principle, where the transmitted signal received via the strongest of the multiple channels is decoded first and subtracted from the received data stream. This is followed by iterative decoding of the next strongest signal and so on. Note that since the second signal is estimated in the presence of one less than the total number of received signals, its estimation variance is generally less than if it were estimated in a non-iterative manner in the presence of all signals. It has been shown however, that the iterative BLAST algorithm offers best performance only if correct signal decoding order is determined. In the case of an incorrect decoding order, the performance of this iterative scheme is sometimes found to be even worse than a conventional non-iterative signal processing technique like LMMSE estimation.
In view of the foregoing, it would be both beneficial and advantageous to provide a receiver that predicts performance of and selects between iterative and non-iterative decoding of symbols based on an intelligent metric.